1. Field of the Invention
The present invention relates to an image forming apparatus having a plurality of paper feed cassettes and, more particularly, to an electrophotographic apparatus, having a plurality of paper feed cassettes, for automatically and preferentially selecting an arbitrary paper feed cassette.
2. Description of the Related Art
Image forming apparatuses having a plurality of paper feed positions for storing a plurality of paper feed cassettes are known. In such a conventional image forming apparatus of this type, in a power-ON or "all clear" operation, a specific paper feed cassette or a paper feed position which is set in the manufacture of the apparatus in advance are automatically selected, regardless of the necessity of a user. That is, conventionally, in a power-ON or "all clear" operation, a specific paper feed cassette automatically selected from the plurality of paper feed cassettes is set in the manufacture of the apparatus in advance.
For this reason, paper sheets in the paper feed cassette automatically selected when a power switch is turned on are not always paper sheets frequently used by a user. In this case, every time the power switch is turned on, or an "all clear" switch is turned on, a required cassette must be reselected by an operator using a console panel, thereby degrading operability. In addition, when the same paper sheets as those in a specific paper feed cassette automatically selected when the power switch is turned on are stored into another paper feed cassette serving as a spare paper feed cassette, and the specific paper feed cassette automatically selected is empty, in a power-ON or the like, the spare paper sheet cassette is not selected, and the specific paper feed cassette containing no paper sheet is selected. For this reason, the operator must manually reselect the spare paper feed cassette containing paper sheets, thereby degrading operability.
In order to solve these problems, a new type of image forming apparatus is disclosed in Jpn. Pat. Appln. KOKAI Publication No. 61-33436. With this apparatus, a user presets the order in which to automatically select the paper feed cassettes when the power switch is turned on or when any one of the cassettes becomes empty. To preset an appropriate order, the user must know what kind of paper sheets are stored in each of the paper feed cassettes. Every time the paper sheets in any paper feed cassette are replaced by those of a different kind, the user must preset a new order in which to select the cassettes automatically.